You cannot come in until he is gone.

I have delayed writing to you, because my great regard for Capt Lewis made me unwilling to shew a haste to fill his place before he was gone, & to counteract also a malignant & unfounded report that I was parting with him from dissatisfaction, a thing impossible either from his conduct or my dispositions towards him. I shall probably recieve a letter from him on his arrival at Philadelphia, informing me when he expects to be back here, and will have the pleasure of communicating to you the earliest conjecture I can form myself for your government. it cannot now be many days.To Lewis Harvie, April 22, 1803

Patrick Lee’s ExplanationLoyal leaders treat trusted subordinates with respect and sensitivity.
Jefferson had previously invited Harvie to become his personal secretary once Meriwether Lewis left for the West. Lewis held that position but was away from Washington City and had been delayed in his preparations for the journey. The President expected to receive a letter from Lewis soon, with an update on his planned departure.

Jefferson’s respect for Lewis was profound. It would be improper to appoint Lewis’ successor until his departure had occurred. There was another reason for the delay. A false report appeared in several newspapers the month before that Lewis was staging a political journey to the Southwest. Delaying Harvie’s appointment would reinforce Jefferson’s confidence in Lewis and lay those false claims to rest.